'79 XS1100F Carb Issues; Poor Performance on the Main Jet.

[bikerphil]

The bike will never run right with Y265 needles, I have tried them and they are not even the right ones for our series carbs. It's a shame that K&L doesn't know this and they don't even care. Smaller diameter needle = excessive fuel.

Ordering from XJ4EVER is easy, just shoot them an email telling them what you want and you should get a quick response back.

[banzaibob]

The bike will never run right with Y265 needles, I have tried them and they are not even the right ones for our series carbs. It's a shame that K&L doesn't know this and they don't even care. Smaller diameter needle = excessive fuel.

Ordering from XJ4EVER is easy, just shoot them an email telling them what you want and you should get a quick response back.

Is he on vacation or something? I've been trying to get in touch with him via e-mail and a conversation on the xj forum since yesterday?

[bikerphil]

Is he on vacation or something? I've been trying to get in touch with him via e-mail and a conversation on the xj forum since yesterday?

I don't know, he usually responds within a day.

[banzaibob]

He got back with me....nice guy. This is what he said:

"Hi Bob, thanks for writing.

Th HCP23265 needles that we offer are the "Y265" needles which are the aftermarket versions of the multi-position 5GZ6 needles.....in other words, you can et the needle "height" within the vac piston at various levels, so as to allow you to "tune" the fuel flow thru the main jet. In your situation, where the engine is running very rich, the needle would need to be clipped in the highest slot, thus lowering the needle within the fuel jet/emulsion tube, and thus resulting in a leaner mixture for most of the travel of the needle thru the jet.

The 1978-79 XS1100 carbs are mess, mainly due to a variety of design modifications that were occuring with the BS34 carbs in those years. For instance, early versions of the BS34 carbs supplied the pilot fuel jets (which are unique to each "versions of these carbs) thru the main fuel jet (and thus require much larger main jets.....so that enough fuel can be used to supply both the main fuel circuit [i[and[/i] the pilot fuel circuits. There was also a block-off screw (or, on later models, a rubber plug) that prevents fuel entry into the pilot fuel jet port from the bottom; the fuel for the pilot circuit has to come thru a drilled passage from the main fuel circuit bore. The lack of the bloock-off screw (or rubber plug) will create an overly-rich fuel condition thru the pilot fuel circuit (which may only manifest itself once the throttle is opened past the 1/3-point----as in your case----when all of a sudden an "overly rich" pilot circuit is now supplemented by the main fuel circuit becoming active.

Let me know if this helps!


Len"

I tried writing him back and thanking him but the forum website won't allow responses for some strange reason. Glitchy.....

So.....he gave me a lot of insight. In many ways it's back to square one. I re-read the original post that I made last winter about this bike....at one time it would rev but only with no air filter. It was still rich however and the plugs would foul.

If anybody regularly corresponds with this Len guy, PLEASE convey my thanks to him.

[bikerphil]

Here is the genuine 5GZ6 on the left and the aftermarket Y265 on the right. There is a subtle difference and like I said, my bike ran poorly with the latter...

It is amazing how little a difference has such a big effect.